10.5" Fossil Hyaenodon Skull - South Dakota

This is a killer fossil, a complete skull of a Hyaenodon from Shannon County, South Dakota.

The skull itself is very impressive and wonderfully prepared. The teeth are all original and only some of the teeth required crack repair. The mandible is overall intact, with the majority of the restoration occurring to both coronoid processes where the bone wasn't recovered. Both mandibular condyles appear to be natural and haven't been restored.

The upper skull is well preserved as well, with no restoration between the orbitals and distal most teeth. Most of the restoration can be found at the posterior end of the skull. The zygomatic/temporal arch bones have been restored on both sides of the specimen and the supra occipital bone appears to have been restored.

The mandible measures 8.3" long by 3.3" tall. The upper skull is roughly 10.5" long. When the upper skull is placed in position on the mandible, the dimensions of the entire skull are 10.5 x 4.5 x 4.3".

Hyaenodons are extinct carnivorous mammals that likely preyed on the oreodonts of the Oligocene. They had large skulls, short necks, very tiny brains, and ranged in size from that of a small dog to that of a large wolf. Though Hyaena is part of their name they have no relation to modern Hyaenas. The name more refers to the likely eating habits of these carnivores as carrion eaters.